Optical probe including predetermined emission wavelength based on patient type

ABSTRACT

A reflectance sensor which can be applied to a patient in a manner which reduces the light energy reaching the detector without first being attenuated by the tissue at the measurement site. Moreover, the reflectance sensor includes emitting devices adapted for use in legacy patient monitoring systems.

RELATED APPLICATIONS

[0001] The present application claims priority to U.S. ProvisionalApplication No. 60/416,492, filed Oct. 4, 2002.

FIELD OF THE INVENTION

[0002] The present invention relates to the field of optical sensors.More specifically, the invention relates to reflectance optical sensors.

BACKGROUND OF THE INVENTION

[0003] Pulse oximetry is a non-invasive procedure for determiningphysiological parameters, such as an oxygen saturation level of arterialblood, pulse rate or the like, by processing received light-energyemissions after they have been attenuated by tissue at a measurementsite. Generally, pulse oximetry involves an optical probe or sensorcomprising one or more emitters, such as light emitting diodes (LEDs),and a photodetector (detector). The LEDs and detector are positioned inproximity with the patients skin. The LEDs emit light energy atpredetermined wavelengths which transmits through the patient's tissue,is attenuated thereby, and is detected by the detector. A signalrepresentative of the detected attenuated light energy is then passedthrough electrical communication to a monitor, such as a pulse oximeter,which processes the signal and determines one or more physiologicalparameters of the tissue at the measurement site.

[0004] Optical probes are generally applied to the measurement site inat least several distinctive manners. For example, one applicationpositions the emitters on a side of the measurement site opposite thedetector such that the light energy passes from one side of themeasurement site, through the tissue, and to the detector positioned onthe other side of the measurement site. Another reflective-typeapplication positions the emitter and detector generally proximate oneanother on the same side of the measurement site. Drawbacks arise inreflectance-type sensors when light energy from the LEDs bounces alongthe surface of the tissue at the measurement site, or otherwise reachesthe detector without passing through the tissue. Such light energy hasnot been attenuated by the tissue, and therefore, distorts or otherwiseprovides noise to the energy being received at the detector.

[0005] Additionally, reflectance-type sensors present various drawbacksduring application, such as, for example, improper positioning on ameasurement site, improper securement to the same, or the like. Thesedrawbacks can increase the likelihood that light energy reaches thedetector without having first been attenuated by the tissue.

[0006] Monitoring systems can also present drawbacks of backwardscompatibility when dealing with newly developed sensor technologies. Forexample, pulse oximeters generally include sets of calibration curvesused to associate data received from the detector with values of dataused to determine the physiological parameters or the parametersthemselves. Thus, as new sensors are developed and used during patientmonitoring, the oximeter may not include an appropriate set ofcalibration curves to appropriately associate detected energy with theforegoing data.

[0007] Embodiments of the present invention seek to overcome some or allof these and other problems.

SUMMARY OF THE INVENTION

[0008] Therefore, a need exists for a reflectance-type sensor(reflectance sensor) which can be applied to a patient in a manner whichreduces the light energy reaching the detector without first beingattenuated by the tissue at the measurement site. Additionally, a needexists for accurately employing new sensors, such as the reflectancesensor, in legacy patient monitoring devices, such as oximeter systemsalready in use. Accordingly, aspects of the invention include areflectance sensor which can be applied to a patient in a manner whichreduces the light energy reaching the detector without first beingattenuated by the tissue at the measurement site. Other aspects includedeployment of the sensor in a manner which is compatible with legacyoximeter systems.

[0009] For purposes of summarizing the invention, certain aspects,advantages and novel features of the invention have been describedherein. Of course, it is to be understood that not necessarily all suchaspects, advantages or features will be embodied in any particularembodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A general architecture that implements the various features ofthe invention will now be described with reference to the drawings. Thedrawings and the associated descriptions are provided to illustrateembodiments of the invention and not to limit the scope of theinvention. Throughout the drawings, reference numbers are re-used toindicate correspondence between referenced elements. In addition, thefirst digit of each reference number indicates the figure in which theelement first appears.

[0011]FIGS. 1A and 1B illustrate exploded perspective views of areflectance sensor according to an embodiment of the invention.

[0012]FIG. 1C illustrates a tissue-side perspective view the assembledreflectance sensor of FIG. 1, according to an embodiment of theinvention.

[0013]FIGS. 2A and 2B illustrate a wrap for attaching the reflectancesensor of FIG. 1, according to an embodiment of the invention.

[0014]FIG. 3 illustrates a tape for attaching the reflectance sensor ofFIG. 1, according to an embodiment of the invention.

[0015]FIG. 4 illustrates a side view of the reflectance sensor of FIG. 1attached to a measurement site, according to an embodiment of theinvention.

[0016]FIG. 5 illustrates a side view of the reflectance sensor of FIG. 1attached to a measurement site, according to another embodiment of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0017] Aspects of the invention include a reflectance sensor includingprotruding lenses and a protruding optical barrier. According to oneembodiment, one lens houses the one or more emitters and the other lenshouses the detector. In addition, the reflectance sensor includes anattachment mechanism which provides sufficient pressure holding thesensor against a measurement site such that the protruding lenses andoptical barrier noninvasively recess into the tissue of the measurementsite. Thus, when the emitter emits light energy through a first lensrecessed into the tissue, the light energy enters the tissue, isattenuated, and is received by the second lens recessed into the tissueand housing the detector. The recessed optical barrier advantageouslyreduces a potential that the light energy can reach the second lens andthen the detector without first being attenuated by the tissue.

[0018] According to one embodiment, the attachment mechanism comprises awrap such as a headband, having an adjustment assembly, such ashook-and-loop material. Adjustment of the adjustment assemblyadvantageously adjusts the pressure exerted by the sensor against themeasurement site. According to another embodiment, the attachmentmechanism comprises an adhesive tape. In yet another embodiment, theattachment mechanism or the sensor may include a biasing member biasedto apply additional force against the sensor toward the measurementsite, thereby advantageously increasing the pressure on the same.

[0019] In yet another embodiment, the emitter emits light energy atwavelengths other than those expected by the legacy oximeter system. Forexample, the emitter can emit light energy at wavelengths chosen suchthat use of the legacy set of calibration curves by the oximeter systemadvantageously produces accurate data.

[0020] To facilitate a complete understanding of the invention, theremainder of the detailed description describes the invention withreference to the drawings.

[0021]FIGS. 1A and 1B illustrate exploded perspective views of areflectance sensor 100 according to an embodiment of the invention. Asshown in FIGS. 1A and 1B, the sensor 100 includes a housing 102,comprising a top portion 104 and a bottom portion 106, a first lens 108housing one or more light energy emission devices such as LEDs, a secondlens 110 housing one or more detectors, and an optical barrier 112.According to one embodiment, the housing 102 positions the first andsecond lenses, 108 and 110, proximate one another, with the opticalbarrier 112 in between, such that each protrudes from a tissue-facingsurface 114 thereof. For example, as shown in FIGS. 1A and 1B, thebottom portion 106 of the housing 102 includes apertures and mountingstructures matchable with the first and second lenses, 108 and 110, andthe optical barrier 112, to position the same to protrude from thesurface 114.

[0022] According to an embodiment, the housing 102 comprises a pliablematerial such as Santoprene™, another thermoplastic elastomer (TPE),silicone, or the like. The upper portion 104 of the housing 102 includesa positioning member 116, such as, for example, a button-stylepositioning member. For example, the positioning member 116 comprise astructure or receives a structure from an attachment mechanism forattaching the sensor 100 to a measurement site. Use of the positioningmember will be disclosed in greater detail with reference to FIGS. 2-4.

[0023] An exemplary embodiment of assembled sensor 100 shown in FIG. 1C,which illustrates the first and second lenses, 108 and 110, and theoptical barrier 112, protruding from surface 114 such that when thesensor 100 is attached to a measurement site, the lenses, 108 and 110,and the optical barrier 112, noninvasively recess into the tissue suchthat light energy from the emitter of the first lens 108 is less likelyto reach the second lens 110 without being attenuated by tissue of themeasurement site.

[0024] According to one embodiment, the first and second lenses, 102 and104, comprise an about 0.200 inch diameter cylinder with an about 0.020inch think flange made of clear silicone or another suitable material,and includes a radius of about 0.100 inches to about 0.150 inches, andpreferably about 0.125 inches.

[0025] Moreover, each lens protrudes through the surface 114approximately about 0.050 inches, but could protrude from approximatelyabout 0.025 inches to about 0.075 inches.

[0026] In one embodiment, the emitters emit light energy at wavelengthsother than those expected by the legacy oximeter system. For example,the emitter can emit light energy at wavelengths chosen such that use ofthe legacy set of calibration curves by the oximeter systemadvantageously produces accurate data. For example, a caregiver mayreceive instructions for choosing a particular sensor from a group ofsensors 100 based on, for example, the type of patient being monitored,the measurement site, the type of oximeter, or the like. According toone embodiment, the sensors 100 may include at least one emitteremitting light energy at wavelengths ranging throughout those useful inpatient monitoring, such as from the visible red to infrared. Morespecifically, the sensors 100 may include an emitter emitting lightenergy at wavelengths ranging from about 650 nm to about 660 nm. Evenmore specifically, the sensors 100 may include an emitter emitting lightenergy at wavelengths of about 654 nm.

[0027] According to an embodiment, the optical barrier 112 comprises anabout 0.050 inch thick black TPE strip about 0.240 inches wide andprotrudes through the surface 114 approximately about 0.020 inches.However, the optical barrier 112 could protrude from approximately about0.010 inches to about 0.040 inches. Also, the optical barrier 112 mayadvantageously be a integral portion of the housing 102.

[0028] Although the sensor 100 is disclosed with reference to itspreferred embodiment, the invention is not intended to be limitedthereby. Rather, a skilled artisan will recognize from the disclosureherein a wide number of alternatives for the sensor 100. For example,the sensor 100 may include flex circuitry, may include plastic or otherfixed-form material, may terminally end in a cable adapter configured toreceive a mating end of a patient cable connected to, for example, anoximeter, may include belt-loop protrusions configured to threadablyreceive an attachment mechanism, snaps, combinations of the same, or thelike.

[0029]FIGS. 2A and 2B illustrate an attachment mechanism comprising awrap 202 for attaching the reflectance sensor 100 to the measurementsite, according to an embodiment of the invention. As shown in FIGS. 2Aand 2B, the wrap 202 includes an adjustment assembly 204 for adjustingthe wrap 202 to form fit, for example, around the measurement site.According to one embodiment, the assembly 204 comprises hook-and-loopmaterial such as Velcro®, however, the assembly 204 may comprise anysuitable asssembly adapted to adjustably encompass the measurement site.FIGS. 2A and 2B also illustrate the wrap 202, such as a headband,including button hole style slots 206 configured to receive thepositioning member 116 of the sensor 100. Moreover, the wrap 200includes indicia 208, such as ruler-style markings, for indicating theapplication of appropriate pressure. For example, according to oneembodiment, the sensor 100 is attached to the wrap 202 by pushing thepositioning member 116 through an appropriate slot 206. The headband canthen be applied to a patient in a friction fit manner. According to oneembodiment, a caregiver can then tighten the headband, for example, apredetermined number of indicia 208, to ensure sufficient pressure isapplied to the sensor 100 to press the lenses 108 and 110 noninvasivelyinto the tissue of the measurement site.

[0030]FIG. 3 illustrates an attachment mechanism comprising a tape 302for attaching the reflectance sensor 100 to the measurement site,according to an embodiment of the invention. As shown in FIG. 3, thetape 302 comprises an adhesive tape of any suitable shape designed tosubstantially fix the sensor 100 to the tissue of the measurement site.According to one embodiment, the tape 302 may include an adhesive sideinitially protected by a release liner layer 304. Additionally, the tape302 may include a slot 306 adapted to advantageously receive thepositioning member 116, thereby potentially providing a caregiver with achoice of attachment mechanism for the sensor 100, depending upon, forexample, the type and condition of the tissue at the measurement site.

[0031]FIG. 4 illustrates a side view of the reflectance sensor 100attached to a measurement site 402, according to an embodiment of theinvention. As shown in FIG. 4, an attachment mechanism 404, such as, forexample, the wrap 202 or the tape 302, applies pressure to the sensor100 pushing the lenses 108 and 110 and the optical barrier 112 into thetissue of the site 402. Similarly, FIG. 5 illustrates a side view of thereflectance sensor 100 attached to the measurement site 402, accordingto another embodiment of the invention. As shown in FIG. 5, anadditional pressure applicator 502, such as a biasing member, isincluded to apply and focus pressure against the sensor 100. In oneembodiment, the pressure application 502 comprises a flexible convexmember having structural memory such that after distortion, the memberexerts force attempting to return to its original shape. Thus, when thepressure applicator 502 is included within the attachment mechanism 404or as a part of the sensor 100, pressure can be more narrowly focusedagainst the sensor 100.

[0032] Although the sensor 100 and the attachment mechanism 404 havebeen disclosed with reference to their preferred embodiment, theinvention is not intended to be limited thereby. Rather, a skilledartisan will recognize from the disclosure herein a wide number ofalternatives either or both of the sensor 100 and the attachmentmechanism 404. For example, the wrap 202 may comprise a foot band, orthe attachment mechanism 404 may comprise any suitable adjustablestructure such as structures adapted to cooperate with, for example, thepositioning member 116 of the sensor 100. Additionally, the surface 114can include adhesive or the like.

[0033] Additionally, other combinations, omissions, substitutions andmodifications will be apparent to the skilled artisan in view of thedisclosure herein. Accordingly, the present invention is not intended tobe limited by the reaction of the preferred embodiments, but is to bedefined by reference to the appended claims.

What is claimed is:
 1. A device for positioning a reflective opticalprobe to a measurement site, the device comprising a attachmentmechanism including a slot adapted to receive a positioning member of areflective optical probe having at least one protruding portion, whereinthe attachment mechanism is configured to apply pressure against theoptical probe when the attachment mechanism is applied to a measurementsite such that at least some of the at least one protruding portionnoninvasively recesses into tissue at the measurement site.
 2. Thedevice of claim 1, further comprising a pressure applicator for focusingpressure against the optical probe.
 3. The device of claim 2, whereinthe pressure applicator comprises a biasing member.
 4. The device ofclaim 3, wherein the biasing member is substantially convex.
 5. Thedevice of claim 1, wherein the attachment mechanism comprises aheadband.
 6. The device of claim 5, further including indicia forinstructing a caregiver on a how to apply a predetermined amount ofpressure on the optical probe.
 7. The device of claim 6, wherein theindicia include ruler-like indicia.
 8. The device of claim 1, whereinthe attachment mechanism comprises an adhesive tape.
 9. The device ofclaim 1, wherein the optical probe is selected by a caregiver based atleast in part on the measurement site.
 10. The device of claim 1,wherein the optical probe includes at least one emitter configured toemit light energy at a wavelength chosen to generate accurate data forlegacy oximeter systems.